ASTM A53 Gr A pipe in structural use

[Geometrico]

ASTM A53 Spec for Steel Pipe has both Grade A and Grade B variants, but the Specification for Structural Steel Buildings in AISC Steel Construction Manual 13th edition "approves" only Gr. B "for use under this Specification" (Sect. A3.1a(3) ). The same was true for the 9th ed.

Grade A seems to be a softer, more ductile material which is readily available in small quantities with certified minimum strength values.

Does anyone here know why ASTM A53 Grade A material is not "approved" for use under the Steel Spec?

 

[racookpe1978]

Structural engineers (rightly!) regard "soft A53" pipe as little better than 2x4's (well, 4x4's actually) when used structurally.

Stronger, more reliable "structural steel pipe" (round things made of steel) is available in the needed quantities in better metals than the stuff used to carry liquids and gasses.

 

[Geometrico]

Thanks for your comments, racookpe1978, but they are unconvincing to me. Reading a little more from the black book...

The commentary to the specification gives a bit of a clue in that it says "This Spec lists those products/materials that are commonly useful to structural engineers and those that have a history of satisfactory performance. Other materials may be suitable for specific applications, but the evaluation of those materials is the responsibility of the engineer specifying them." That is encouraging.

It goes on to say that "A53 Gr B is included because it is the most readily available product in the US. ... In addition pipe is produced to other specs that meet the strength, ductility and weldability requirements of materials in Section A3." Ah, availability is the reason? Well, that is the reason I want to use A53 gr A in the first place.

Then the commentary talks about A500 Gr A and how it does not meet the requirement for certain connection details of Fy/Fu ? 0.8 because of the way Fy is defined in the A500 spec.

Seems to me that if we are careful with the connection detailing and we are not scared of the "responsibility to evaluate those materials" then A53 Gr. A material can be readily used.

 

[HereTwoLearn]

I have never used A53 Gr A Pipe. However, I have used pipe not listed specifically in the AISC code.

Among other things, I looked at:
1) Fabrication of pipe (cold rolled vs hot rolled/formed)
2) Inspection / testing of weld seam at the mill, assuming cold rolled.
3) Aesthetics of the weld seam.
4) Tolerances on wall thickness.
5) Weldability. One thing that gives me peace of mind is if the pipe is listed in AWS D1.1 as a prequalified type of pipe for a common type of welding.
6) fy / fu
7) Fabricator's preference and experience.

I have used grades of API 5L after this review.

 

[racookpe1978]

Oh, I fully agree.

A "pipe" (a round solid thing made in specific shapes and wall thickness of various materials and by various processes to hold liquids and gasses) can certainly be used in engineering projects as a "round steel beam".

No question about that.

Just recognize that particular grades of steel and ways of fabricating "round steel beams" will give you a much stronger, more weldable, more consistant beam at lower weight (wall thickness) for structural purposes than genreic A53 "pipe" of the same OD.

But if you recognize the lower limits and abilities of A53 pipe when used as structural steel, and those limits meet your needs of weight, time, availability and cost, go ahead. Safely and prudently.

 

[MultiVar]

My main hesitation would be: LAWYERS!

You would have a structural element that has been "evaluated" and "approved" by one lone person (hereafter referred to as "Defendant"), rather than a huge .org, with a LONGstanding history of such activities, and published, peer-reviewed handbooks which all P.E.'s bow down before. CYA writ large, if you will.

Just a thought. ;')